We present an implantable probe utilizing single-pixel confocal microscopy based on a scanning micro- mirror for one-photon brain imaging. Addressing the specific needs of expansive fields of view (FOV) and extended working distances, this multi-wavelength, multi-modal probe achieves a subcellular resolution of 1.5 µm within a FOV of roughly 500 μm and a working distance of 250 μm. Our design integrates off- the-shelf optics with the cost-efficiency of inexpensive 3D printing, offering an affordable and effective imaging tool. A customized oval-shaped electrostatic mirror enhances the imaging capability. Validation, using wavelengths of 445, 515, and 561 nm on both microbeads and Brainbow mice specimens, emphasizes the probe's potential for advancing one-photon brain imaging techniques in freely moving animals. The economic and accessible nature of this tool holds promise for broader applications in neuroscience research.
KEYWORDS: Imaging systems, Confocal microscopy, Real time imaging, In vivo imaging, Diagnostics, Cancer, Tissues, Mirrors, Microelectromechanical systems, Image resolution
A multiphoton, multimodal miniaturized microscope for mice brain imaging is developed. The optical design to provide a compact and lightweight probe uses small lenses, of less than 4mm diameter, selected for performance using raytracing software. The microscope is designed to maintain diffraction-limited resolution for imaging reporters GCAMP6 and eYFP or performing near-infra-red reflection confocal microscopy. A Mai-Tai femtosecond laser is used to provide a 920nm pulse laser, an Insight X3 laser to provide a 960nm pulse laser, and a separate 785nm continuous wave (CW) laser to support NIR reflection with optical sectioning capability with a high signal-to-noise ratio. The miniaturized system was tested as a benchtop prototype using a reflection target, green fluorescent protein, and enhanced yellow fluorescent protein. The resolution for all three wavelengths is less than 2μm. A customized parametric resonance electrostatic MEMS scanner provided the beam scanning of 1.8mm in diameter, resulting in a 350μm by 350μm field of view with a numerical aperture of 0.42, at a working distance of about 350μm. A 4μm core single-mode fiber and a photodiode collect the reflection beam in the confocal mode. Two dichroic mirrors out of the probe are used to combine all three beams toward the probe. Two dichroic mirrors are used for two emission wavelength separations.
Ring resonators have been vastly considered to address the demand for future needs of smaller miniature array to reach compact and more sensitive ultrasound detectors. In this work we proposed a novel mechanically induced high sensitivity for a ring on an slotted membrane with relatively low-cost polymer material, roll to roll manufacturing ability, and less temperature-sensitivity. The results showing a 50 % sensitivity increase on the most sensitive device structure on simple membrane which has been reported. We also proposed its fabrication method by two-step nano-imprint lithography followed by AFM tip to make the slots on the membrane. This device could add benefits of early diseases detection in ultrasound biomedical imaging. Also, in a combination of an array with other ring resonators can cover larger dynamic range and frequency bandwidth.
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